Crystal structure, Hirshfeld surface analysis, molecular modeling, electrochemical properties, and potential medicinal activity of a novel binuclear Co(II) complex

A quinoxaline-based ligand, 6,7-dimethyl-2,3-di(2-pyridyl)quinoxaline (Me2dpq), and its unique binuclear Co(II)-Me2dpq complex were prepared and analyzed using single crystal X-ray diffraction and several spectroscopy techniques. Hirshfeld surface analyses were also used to clarify the Me2dpq ligand and the Co(II)-Me2dpq crystal packing. The Co(II)-Me2dpq complex crystallized in triclinic P-1 space group and exhibited a distorted trigonal bipyramidal geometry around the cobalt(II) ion. Each Co(II) ion coordinated to a Me2dpq ligand through two N donor centers from pyridyl and quinoxaline rings along with a terminal Cl and two bridged Cl atoms. The binding properties of the ligand and its complex with CT-DNA were studied by several techniques, namely UV-Vis spectroscopy, fluorescence quenching, viscosity measurements, thermal denaturation, and gel electrophoresis. The CT-DNA binding interaction tests demonstrated that both the Co(II)-Me2dpq complex and its parent ligand bind to DNA in an intercalative way. The antioxidant studies of the novel Co(II)-Me2dpq complex illustrated significant activity against DPPH center dot and OH center dot<middle dot>$$ {\mathrm{OH}}<^>{\bullet \cdotp } $$ radicals. The in vitro cytotoxic effect of Me2dpq ligand and its Co(II)-complex on MCF-7 and Hep-G2 tumor cell lines was evaluated by using the MTT assay. The studies showed that the Co(II)-Me2dpq complex had superior activity toward the tested cell lines. Molecular docking studies of synthesized compounds were employed to figure out the way they would associate with a biologically macromolecular target B-DNA (PDB: 1BNA). Thus, this study is anticipated to provide novel opportunities for the successful utilization of the synthesized compounds in many medical domains. Me2dpq, a bioactive polypyridyl quinoxaline-based ligand, and its unique binuclear Co(II)-Me2dpq complex were synthesized and characterized by single crystal X-ray diffraction and other spectroscopic approaches. The ligand and Co(II)-complex were tested for DNA binding, antioxidant scavenging, and cytotoxicity. DNA binding mechanism was investigated using molecular docking. image